Types of soft tissue sarcomas

The type of soft tissue sarcoma you have is important. Knowing this helps your doctor decide which treatment you need.

Soft tissue sarcomas can develop in the connective and supporting tissues in the body. These include:

• fat
• muscle
• blood vessels
• deep skin tissues
• nerves
• tendons and ligaments
• the tissues around the joints

There are many different types of soft tissue sarcomas. Many are very rare. Below are some of the more common types.

Leiomyosarcoma

Leiomyosarcoma is the most common type of soft tissue sarcoma in adults. It is a type of smooth muscle tumour. This is the type of muscle that you use without thinking about it (involuntary muscle).

Involuntary muscle forms the walls of the womb, digestive system and blood vessels.

Leiomyosarcomas can grow in the:

• tummy (abdomen)
• deeper tummy (retroperitoneum)
• large blood vessels
• womb (uterus)
• skin
• limbs

Leiomyosarcoma that starts in the muscle of the womb is also called uterine leiomyosarcoma.

Inflammatory leiomyosarcoma 

Another type of smooth muscle cancer in adults is inflammatory leiomyosarcoma. This type of sarcoma tends to grow in the:

• deep soft tissues of the legs
• chest and tummy (abdomen)
• deeper tummy (retroperitoneum)

Liposarcoma

Liposarcomas develop from fatty tissue and can grow anywhere in the body. The most common sites are the thigh and deeper tummy (retroperitoneum). They usually show up as soft lumps.

About 20 out of every 100 (20%) soft tissue sarcomas in adults are liposarcomas.

Types of fatty tissue tumours

Types of cancerous (malignant) tumours that grow from fatty tissue are:

• well differentiated liposarcoma
• dedifferentiated liposarcoma
• myxoid liposarcoma
• pleomorphic liposarcoma

Fibrosarcomas

Fibrosarcomas are a type of fibroblastic tumour. This means they grow from cells in fibrous tissue.

Fibrosarcomas are rare and form about 1 out of every 100 (1%) soft tissue sarcomas. They can grow in the:

• deep tissues of the arms or legs
• chest and tummy (abdomen)
• head and neck

Other types of fibroblastic tumours

Other types that are cancerous (malignant) include:

• solitary fibrous tumour
• myxofibrosarcoma
• low grade fibromyxoid sarcoma
• sclerosing epithelioid fibrosarcoma

Rhabdomyosarcomas

Rhabdomyosarcomas develop from skeletal (striated) muscle cells. This is the type of muscle that you can control (voluntary muscle). Rhabdomyosarcomas can develop anywhere in the body. 

There are several types:

• embryonal rhabdomyosarcomas (more common in children, rare in adolescents and adults)
• alveolar rhabdomyosarcomas (more common in adolescents and adults)
• pleomorphic rhabdomyosarcoma (most common in adults)
• spindle cell or sclerosing rhabdomyosarcoma
• ectomesenchymoma

Soft tissue Ewing sarcomas

Ewing sarcomas most commonly start in a bone. Rarely, it can start in soft tissues. Soft tissue Ewing sarcoma is called extraskeletal Ewing sarcoma. Extraskeletal means they are outside the bone.

These soft tissue tumours behave a bit differently from other types of soft tissue sarcoma. They're usually treated in the same way as Ewing sarcoma that starts in the bone.

Synovial sarcomas

Synovial sarcomas are a type of tumour of uncertain differentiation. This means the cell of origin is unknown. These sarcomas are made up of cells that don’t look like any specific type of soft tissue. So, it is hard to say where the cancer started.

Synovial sarcomas most commonly grow around the knee or ankle joints. It can also start in other joints such as the hip or shoulder.

Although they are called synovial sarcomas, they don’t start in the tissue that lines the joints (synovial tissue). They can be found in areas where there is no synovial tissue. This includes the head and neck. 

These sarcomas usually show up as hard lumps.  But they can be present for some time before they start to grow bigger. They're more common in young adults and in males.

Other types of tumours of uncertain origin

Some other types that are cancerous (malignant) are:

• epithelioid sarcoma
• alveolar soft part sarcoma
• clear cell sarcoma
• extraskeletal myxoid chondrosarcoma
• desmoplastic small round cell tumour
• rhabdoid tumour
• perivascular epithelioid tumour

Vascular tumours

Angiosarcoma

Angiosarcoma is a type of vascular tumour. Vascular tumours develop from endothelial cells. These cells make up the walls of blood or lymphatic vessels.

Angiosarcomas usually start in the skin or superficial cells. In some cases, it is linked to chronic lymphoedema. Lymphoedema is a type of swelling. It might happen after surgery or radiotherapy to lymph nodes as part of cancer treatment.

Women with chronic arm lymphoedema following breast removal (mastectomy) can develop angiosarcoma. It can happen in the swollen arm. This is rare. It is also known as Stewart-Treves syndrome. It usually takes many years to develop.

Angiosarcoma of the heart

Tumours that affect the heart are very rare. Most tumours that start in the heart are not cancer, they are benign. About 10 in every 100 (10%) are cancers (malignant). Most commonly these are soft tissue sarcomas.

Other types of vascular tumours

Kaposi’s sarcoma

Kaposi's sarcoma is a type of vascular tumour. It is called an intermediate tumour. This means they grow and spread to nearby tissues and organs. They don’t spread to other parts of the body.

Kaposi’s sarcoma develops from cells called endothelial cells. These cells line the blood and lymph vessels. Most cases occur in the skin. They can also develop in the body's internal organs.

Kaposi’s sarcoma is caused by Human Herpes Virus 8 infection (HHV8). It is also known as Kaposi’s sarcoma associated herpesvirus (KSHV). Many people have HHV8. Most do not develop Kaposi’s sarcoma. But this virus can sometimes cause Kaposi’s sarcoma in people with lowered immunity. This is mainly in people with:

• HIV
• AIDS

People taking medicines to suppress their immunity also have an increased risk of developing Kaposi’s sarcoma. This is usually after an organ transplant.

Other types are associated with people descended from:

• Africa
• Eastern Europe
• the Mediterranean

Kaposi’s sarcoma is treated differently from many soft tissue sarcomas. Treatment depends on:

• the type of Kaposi’s sarcoma
• where the cancer is in the body

Epithelioid haemangioendothelioma

These tumours start in soft tissues or internal organs, such as the lungs.

Malignant peripheral nerve sheath tumours (MPNST)

Malignant peripheral nerve sheath tumours are a type of peripheral nerve sheath tumour. These cancers begin in the layer (nerve sheath) that cover the peripheral nerves. Peripheral nerves send messages between the brain and spinal cord and the rest of the body.

MPNST are rare in the general population. It can happen in people with neurofibromatosis type 1(NF1). They can grow anywhere in the body. The most common sites are the:

• legs
• deeper tummy (retroperitoneum)

Other types of peripheral nerve sheath tumours 

Other types that may be cancerous include:

• melanotic malignant nerve sheath tumour
• granular cell tumour
• perineurioma

Gastrointestinal Stromal Tumours (GISTs)

A GIST is a rare type of sarcoma found in the digestive system (gastrointestinal system). GISTs can grow in any part of the digestive system, but the most common sites are the stomach and small bowel.

GISTs start in cells in the wall of the digestive system that controls the movement of the gut. Cancer starts when these cells begin to grow in an uncontrolled way.

Non cancerous (benign) gastrointestinal stromal tumours are called MicroGIST.

Follicular dendritic cell sarcoma

Follicular dendritic cell sarcoma (FDC sarcoma) is a very rare type of sarcoma. Some of its symptoms, such as painless swollen lymph nodes , are like that of lymphoma . Lymphoma is a type of blood cancer.

Doctors treat FDC sarcoma as a soft tissue sarcoma. FDC sarcoma develops from specialised cells in the lymph nodes. The lymph nodes are part of the lymphatic system, which helps to fight infection.

Fibromatosis

Fibromatosis is not a sarcoma, but it is often treated by sarcoma specialists. They are closely monitored as these tumours can grow large. A large tumour can affect your quality of life.

Fibromatosis is not cancer and grows from deep connective tissues. It does not spread around the body but can spread into nearby tissues. It is also called aggressive fibromatosis or a desmoid tumour. 

Fibromatosis is rare. It can start anywhere in the body but is more common in the:

• arms or legs
• tummy wall (abdominal wall)
• tissue that attaches the small and large bowel to the back wall of the tummy (mesentery)